Heath

I have 44.5mm (1.75") ports and I'm looking for recommendations on intake runner length. The car will see a blend of street and track use but predominantly street, so torque will be a factor. I would rather have decent torque than maximum hp. I'm not saying hp isn't important but I would prefer a happy medium.

The setup is utilizing a Weber 48 IDA with 44mm venturis.

I intentionally left the intake tubes a bit long so that I may cut them to desired length.

After I figure out the intake I'll work on the exhaust

Any and all help is appreciated.

j9fd3s

i think the intake length is related to the port timing and exhaust length, so mazda's numbers are a guideline unless you have the same port timing.



competition book says the lengths they used are 155mm F and 165R for the rx7 and 135mm and 145mm in the rx3

Heath

Thanks for the info. So they use different length runners for the front and rear housings? I assumed they would be the same.

j9fd3s

yeah, engine's not level in the car.

j9fd3s

weird, i tried to attach an SAE paper, recent tech 84-7-11



they have power graphs for intake length, exhaust length, and port timings

Heath

Thanks for attempting. If you can figure it out please do I would love to check it out.

j9fd3s

whats your email?

Heath

morganf1@charter.net

Thanks!

PDF

I also would be interested in the SAE paper. richard@greenbrothers.co.nz if it's not too much trouble.